Computer hardware and software have been developed with the ability to multitask to increase the effectiveness and efficiency of work that is performed on computing devices, for example, personal computers (“PCs”) or servers. Such multitasking may be carried out by a single processor in a single PC, where the single processor simultaneously executes instructions from multiple software programs. For example, a user of the PC may open a software program for the rendering of a drawing. While the software program is rendering the drawing, the user may have also opened a word processing program and started to type into a document. The processor of the PC may switch from processing the keystrokes of the word processing program to the rendering of the drawing in the intervals between keystrokes. Even though these intervals are quite short in terms of human time, these intervals may be quite lengthy for the processor of the PC. Thus, intervals during the execution of a primary operation such as these may be used to accomplish a secondary purpose, e.g., rendering the drawing. This is a very simple example of multitasking and the hardware and software mechanisms to implement a multitasking scheme for such a simple example may be very complex, requiring steps such as the prioritizing of tasks and the allocation of processor resources.
More complex examples of multitasking arise in situations where there is a computer network arranged in a client-server relationship. For example, the server may have multiple processors with each processor processing separate tasks while receiving requests from clients on the network. The clients may be, for example, PCs, printers, modems, etc, which require services from one of the server processors in order to run various tasks. In this type of environment, hundreds of clients may be simultaneously requesting services from the server. A process for implementing multitasking in such an environment must be extremely complicated to efficiently arrange and process each of the requests. Generally, multitasking has positive connotations because of the improved efficiency associated with the ability to perform more than one process at one time.
However, multitasking has finite limitations because it is dependent on various factors such as the operating characteristics of the processor(s), memory, and I/O devices. For example, if a processor in a server is performing tasks for several clients, and the resources of that processor are being completely utilized, the processor can no longer multitask a new client request because of insufficient processor resources. Furthermore, a requested client task may be invalid preventing the server processor from effectively processing the task. In this situation the processor may continue to process the task without ever finishing because of the problem with the task, e.g., improper coding of the task resulting in an endless processing loop. A processor that is caught in an endless loop cannot be released to process other tasks. The processor may then simply crash and, in any case, needs to be restarted. In either case, the advantages of multitasking are not achieved.